1. Field of the Invention
The present invention relates to an oxide semiconductor.
2. Description of the Related Art
The research on a structure of In—Ga—Zn oxide started with the synthesis of the In—Ga—Zn oxide by Kimizuka, Nakamura, et al. from National Institute for Research in Inorganic Materials. They reported that an In—Ga—Zn oxide had a homologous structure and was represented by a composition formula, InGaO3(ZnO)m (m is a natural number) (see Patent Document 1 to Patent Document 6, and Non-Patent Document 1 to Non-Patent Document 4).
After that, a report about a transistor including amorphous In—Ga—Zn oxide was released (see Non-Patent Document 5). Since then, various research institutions and companies have actively researched and developed applied technology of In—Ga—Zn oxide.